May has said the government’s believes to increasing capacity at Heathrow was important for “the ambitions we have as a trading nation for the future”.

And she has defended allowing Johnson to skip the vote. “The foreign secretary early next week will be what I would describe as the living embodiment of global Britain,” she said.

“He will be out there actually showing the UK’s continued presence around the world and the work that the UK continues to do around the world with our diplomacy, working on so many of the issues and challenges that we face across the world today.”

Jeremy Corbyn has decided to allow Labour MPs a free vote on the expansion plans.

His decision follows big pressure from trade unions like Unite and the GMB, who have long campaigned for a third runway as the key to more jobs in construction, travel and retail.

It also means that Shadow Chancellor John McDonnell, whose London constituency is under the Heathrow flight path, can continue his opposition to the third airport.

On Sunday night, Len McCluskey, the head of the Unite union, wrote to all Labour MPs urging them to back the expansion on Monday, saying it was “the opportunity to create hundreds of thousands of new jobs”, putting him at odds with Corbyn.

They wrote that supporting the scheme is right “in principle”, saying: “It’ll create up to 180,000 new jobs across the country, delivering growth and connectivity for our constituents.

“As this project will span multiple parliaments – including, we hope, a Labour government – it’s our responsibility to secure strong cross-party backing for this project.”

The MPs disagreed that the expansion plan failed to meet its four tests for support: increased capacity, C02 reduction, minimised noise and shared benefits across the UK, writing: “Monday night’s vote is not a blank cheque – the huge benefits from expansion can only be achieved if Heathrow also meets stringent tests on air quality and noise.

“We will work to ensure legally binding safeguards are in place that will mean a new runway can only be built if it is environmentally sustainable.”

Ahead of the vote, officials said the expansion of Heathrow would create 114,000 extra jobs in the area around the airport by 2030, with an extra 16 million long-haul seats by 2040.

It would represent the first full-length runway in the south east since the Second World War, the Department for Transport said.

Opponents have attacked the scheme on environmental, noise and financial grounds grounds, with Friends of the Earth saying it was “morally reprehensible” and would see the enlarged Heathrow emitting as much carbon as the whole of Portugal.